Silk-screen printing paste



Patented Sept. 9, 1952 summing in =s1i1 -se1mnn PRINTING PASTE FrankEnoch Ker-ridge and Gyril Stanley' Gouper, London, Englaniassignors toJohnsonf Matthey & Company Limited,'Londom'xEngland, a

. Britishcompany N Drawing. Application July 18; 149,'Serial No.

.11oa44 4. In Great Britain July 27, 1948 earthenware. and. chinaand'iis more particularly concerned with the decorationofi suchi'baseswith "a design or decoration irr platinum'iori having a platinumorsilverlikeappearance.

. Platinum decorations. or decorations having a platinum or silverappearance have in eneral heretofore beenwproduced on glass, china or:ear'thenware .by fthe use. orone of" theifollowing j materialanam'ely:I ,1

(1 'Liquid platinum whichoonsi'sts essential- ,ly. of -..a.;.so1uti0nof..platinum sulphoresinate in suitable. solvents; M

'(2) Liquid white gold (popularly known as liquid silver) which consistsessentially of a :mixture; in suitablesolvents, l )of platinum and:gold. sulphoresinates,.-a mixtureof. palladium and 1 gold.sulphoresinates, on :a mixture ofz platinum,

palladium, and-goldsulphoresinates;

(3) .Liquid bumish white-gold (sometimes known as liquidburnish-silver?)econsistingxof a suspension of gold or a gold compoundin a solution of gold aridplatinum sulphoresinates, or of goldandpalladium sulphoresinates: andfinfs'ome cases; including a mercurycompound: I

' (4)Finelydivided (usuallyprecipitatedrplatinum powder, with or withouta powdered mercury compound;

' (5) Einely'dividd platinum-or palladiumswith goldpowder, with orwithout--a 'powdered mercury compound.

All ottheabove materials contain an adhesion;

.ly l-rubber: stampnprintin'g or zengraved .aplate reprinting. l A w v 1.l'llhenubber stamp m'ethodywhilstbeingwimpie =-':and' rapidinusty-results in J a 'idesign -whiclig is deckinginrihnss-and=sharpnessofbiitline no,

moreoven aoes not-enable ceramic colours to-be I aiLpriintedsimultaneously in register with the platiinummrplatinum-like decoration.

' -With engraved-plate or copper-plate printing a transfer -is "preparedby engraving' or etchinga design on a copper "or glass plate; fillingthe inter- "stices or depressions so formed with-the printing paste,applying a sheet ofgummd tissuepaper,

'gummed' side downwards to the'coated'plate' and then removingthe paper,which-nowcarries the plied; whilstthe paste is: still moist or stickywith "the "design-carrying side downwards, to l the article. "The tissuepaper is then soaked on and the-article fired. l i This'methodj'in thehandset a 'sk'illed operator,

gives a' deooration of good q'ualityi but, as the design is applied tothe 1 ware in the moist state; it cainnot *be used'for applyingboth-platinum, Ora platinum-like decoration and a ceramic ool'oursimultaneously in register. Afurtherdisadvanea ceramic =colour transfer*by the silk screen printing method. 7 -Silk-scren printing; whetherused ror decorating'an artiCle by direct application" or for the"preparation of transfers-"offers" advantages over i theothermethods'referred toin that theapparatuseemployed is inexpensive, avariety of decorative efiects are obtainable and -"print pfhighdualityand 1 well-defined outlines can -be readily produced byrelatively unskilled workers.

\ 'Pastes embodying 'the "above mentioned-'matepreparationbftransfers"rials as heretofore" constitutedior :usewith; the rubberstamp"orengraved plate printingmethods are quite" unsuited for use withthe silk-screen printing method, particularly in the' easeofthe Itwi-lt=beappreciated from-a Y consideration of 1 the above that, itaplatinumpaste or one-giving a :platinum or's'ilver-like appearance; :wereprovidedg which could besatisfactorily applied by the "silk-screenprinting me'thod, very considerable advantages would accrue both fromthe artistic and the commercial -aspects. In "the first'pla'ce.

it-would-be-possibleto decorate an article with a d sign in platinum,which would have amore {pleasing f-efiect thanfi those hithertoobtainable with the hitherto known methods, owing to"'theimproveddfini'tion or the outlines and 'the'fact that it becomespossible to print a ceramic colour design in register with the platinum,and secondly, the process of decorating can be carried out relativelyinexpensively.

Silk-screen printing, however, produces a. very thick deposit and whilstthis is in many instances, particularly in the case of ceramic enamels,greatly to be desired, it may be that, in the case of a platinumdecoration, the cost of the platinum may outweigh the advantagesattainable by the use of his method. Attempts to produce a thinnerdeposit by employing a low platinum, or like.

precious metal, to medium ratio will result in unsat s ory P g owing tothe low proportion of solid in the paste, and frequently in flowing ofthe prints and loss of sharpness of outline before drying.

An object of the invention is to overcome the I I above disadvantagesand to provide an improved platinum paste suitable for directapplication to an article to be decorated by the silk-screen printingmethod or for the preparation by the silk-screen printing method, oftransfers intended for subsequent application to an article.

Another object is to enable a thin deposit of platinum to be applied toa heat resisting base by the silk-screen printing method.

, A further object is to enable the thickness of the platinum deposit tobe readily controllable.

Another object is to provide a silk-screen printing paste includingplatinum powder and a volatilisable solid, which will volatilise withoutcarbonising during the subsequent 'firingof a heat-resisting basedecorated with the paste.-

- A still further object is to provide a silk-screen printing pastecomprising platinum powder, a flux or adhesion promotingagent having amelting point not higher than 500 C., an organic silk-screen printingmedium or vehicle, and a volatilisable solid.

By including a volatilisable solid in the paste, the amount of preciousmetal in the paste, and hence the thickness of the final precious metalfilm obtained after firing, may be varied as desired, sinceby suitablyproportioning the amount of volatilisable solid included, the ratio ofliquid to total solids in the paste may bemaintained in the correctproportion to give good printing qualities.

The volatilisable solid may consist of any solid which volatilisescompletely at a low temperature, but we have found that certain organicmaterials, such as oxanilide, aoetanilide or anthracene are moresuitable than volatilisable inorganic materials, such as ammoniumchloride. Of-the organic materials mentioned, we prefer to useanthracene.

- The proportion of medium to solid substances is preferably 1-4 partsof medium to 2 parts of solid, the exact proportions depending on theparticle: size. of the solids and the viscosity of the medium.

The organic medium will comprise a -film- .forming ingredient dissolvedin a solvent, for

example it may be a cellulose derivative or a natural or synthetic resinor resins or a'mixture thereof dissolved in-a solvent or solvent mixturehaving a rate of evaporation suitable for silkscreenprinting. Forexample, the medium may consist of nitrocellulose dissolved in amyland/or ethyl lactate vor of colophony dissolved in pine Dill, v I I Theflux may be alead borosilicate or a lead alkali borosilicate fiuxor .abismuth compound, such asbismuth oxide or, oxychloride.

' Per cent by weight (1) Platinum powder 40 Mercurous chloride 10 Lowfusing lead borosilicate flux 3.5 volatilisable solid (anthracene) 2.5'Plasticised nitrocellulose medium 44 e the constituents beinggroundtogether toform a paste. v

i Per cent by weight (2) Platinum powder 40 Mercurous chloride 10 Lowfusing lead borosilicate flux 3.5 volatilisable solid (anthracene) 2.5

Plasticised resinous medium "44 the constituents being ground togetherto form a paste.

In the case of the decoration of a pottery article, a lower percentageof flux may be used, since a higher firing temperature can be employedthan with glass.

The preferred composition of the individual constituents of our improvedpaste is as follows:

Flux or adhesion promoting constituent Although many lead borosilicateor lead alkali borosilicate fluxes which melt at a temperature of400-500 C., or a bismuth compound may be used, we have found that themost satisfactory results are obtained by using a flux having thefollowing composition:

Lead monbnd'e (PbO) Y Boric oxide,(B: )a) 7.0

Silica (SiOz), v.5

Medium If a medium based on a cellulose derivative is employed, thefollowing composition will be found suitable:

Per cent by weight Amyl lactate 56 Ethyl lactate 20Nitrocelluloselmedium viscosity) 8 Methyl abietate '8 Castor oil '8 If aresinous medium is employed, the following composition will be foundsuitable::

. Per centby weight Pine oil '10 Colophony 20 Methyl abietate 5 Castoroil 5 In the use of our improved paste for the dewration, for example,of a substantially flat article of glassythe paste is applied to thearticle, so

astto form any desireddesign--thereon,.--by the silk-screen printingmethod, and allowed to'dry.

The coated articleis then fired at. a temperature Per cent by weightwithin the range of 500-4350 C. depending on the type of glass, to burnaway the organic matter and cause the precious metal or metals to adherefirmly to the article.

If the base being decorated is of earthenware or china, the firingtemperature is preferably between 650 and 800 C.

The decoration, after firing, will present a matt surface, and should belightly scoured with sand or burnished with agate so as to produce abright effect.

When the paste is to be used for preparing a transfer, the paste isapplied, in any desired design, to a sheet of transfer paper by thesilkscreen printing method and is again allowed to dry. To decorate anarticle, the transfer paper with the design thereon is applied to thearticle and the design transferred to the surface thereof by thewell-known slide-off method. The article is then fired at a suitabletemperature, i. e. within the range of 500-650 C. in the case of a glassarticle and 65-0-800 C. in the case of earthenware or china. The fireddesign may, in this case also, be lightly burnished. It is to beunderstood that the improved paste may be printed so as to register witha vitreous enamel or ceramic colour in a combined platinum orsilver-like and enamel decoration.

As will be appreciated, our invention enables an article to be providedwith a decoration having the appearance of silver, but which does nottarnish on exposure to air.

What we claim is:

1. A silk-screen printing paste for the preparation of a transfer or fordirect application to a heat-resisting base, said paste comprising amixture of platinum powder, anthracene, a ceramic flux and an organicvehicle consisting of 56% by weight of amyl lactate, 20% by weight ofethyl lactate, 8% by weight of nitrocellulose, 8% by weight of methylabietate and 8% by weight of castor oil and the relative proportions ofplatinum powder, ceramic flux and anthracene to liquid vehicle beingalways substantially 2 parts of solids to 1-4 parts of vehicle.

2. A silk-screen printing paste for the preparation of a transfer or fordirect application to a glass base, said paste comprising a mixture ofthe following constituents in the following proportions by weight,namely:

Per cent Platinum powder 40 Mercurous chloride 10 Lead borosilicate flux3.5 Anthracene 2.5

Solution containing plasticized nitrocellulose 44 3. A silk-screenprinting paste for the preparation of a transfer or for directapplication to a heat-resisting base, said paste consisting essentiallyof a platinum powder-ceramic flux mixture and anthracene, said platinumpowder-ceramic flux and anthracene constituting solid ingredients, andan organic screening vehicle comprising nitrocellulose dissolved in asolvent selected from the group consisting of amyl lactate, ethyllactate and mixtures thereof, and the relative proportion of thecombined amounts of platinum powder-ceramic flux mixture and anthraceneto liquid vehicle being always substantially two parts of solids to 1-4parts of vehicle. 7

4. A silk-screen printing paste for the preparation of a transfer or fordirect application to a heat-resisting base, said paste consistingessentially of a platinum power-lead borosilicate flux mixture andanthracene, said platinum powderlead borosilicate flux and anthraceneconstituting solid ingredients, and an organic screening vehiclecomprising nitrocellulose dissolved in a solvent selected from the groupconsisting of amyl lactate, ethyl lactate and mixtures thereof, and therelative proportion of the combined amounts of platinum powder-leadborosilicate flux mixture and anthracene to liquid vehicle being alwayssubstantially 2 parts of solids to 1-4 parts of vehicle.

5. A silk-screen printing paste for the preparation of a transfer or fordirect application to a heat-resisting base, said paste consistingessentially of a platinum powder-ceramic flux mixture, said ceramic fluxbeing selected from the group consisting of bismuth oxide and bismuthoxychloride, and anthracene, said platinum pow der-ceramic flux andanthracene constituting solid ingredients, and an organic screeningvehicle comprising nitrocellulose dissolved in a solvent selected fromthe group consisting of amyl lactate, ethyl lactate and mixturesthereof, and the relative proportion of the combined amounts of platinumpowder-ceramic flux mixture and anthracene to liquid vehicle beingalways substantially 2 parts of solids to 1-4 parts of vehicle.

FRANK ENOCH KERRIDGE. CYRIL STANLEY COUPER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 255,421 Dode Mar. 28, 1882460,358 Buttler Sept. 29, 1891 1,752,462 Smith Apr. 1, 1930 2,113,449Hoffman et a1 Apr. 5, 1938 2,190,210 Kaber Feb. 1.3, 1940 2,287,053Murphy June 23, 1942 2,294,760 Morris Sept. 1, 1942 2,318,803 Schneideret al. May 11, 1943 2,452,805 Sussenbach Nov. 2, 1948 FOREIGN PATENTSNumber Country Date 7. 688 Great Britain 1892 9,261 Great Britain 1894428,743 Great Britain May 17, 1935 526,853 Great Britain Sept. 26, 1940566,718 Great Britain June 10, 1945

3. A SILK-SCREEN PRINTING PASTE FOR THE PREPARATION OF A TRANSFER OR FORDIRECT APPLICATION TO A HEAT-RESISTING BASE, SAID PASTE CONSISTINGESSENTIALLY OF A PLATINUM POWDER-CERAMIC FLUX MIXTURE AND ANTHRACENE,SAID PLATINUM POWDER-CERAMIC FLUX AND ANTHRACENE CONSTITUTING SOLIDINGREDIENTS, AND AN ORGANIC SCREENING VEHICLE COMPRISING NITROCELLULOSEDISSOLVED IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF AMYLLACTATE, ETHYL LACTATE AND MIXTURES THEREOF, AND THE RELATIVE PROPORTIONOF THE COMBINED AMOUNTS OF PLATINUM POWDER-CERAMIC FLUX MIXTURE ANDANTHRACENE TO LIQUID VEHICLE BEING ALWAYS SUBSTANTIALLY TWO PARTS OFSOLIDS TO 1-4 PARTS OF VEHICLE.